Impacto del clavicornio del agua Tropisternus sp. (Coleoptera: Hydrophilidae) sobre larvas de Culex pipiens Say (Diptera: Culicidae) [por] Humberto Quiroz Martínez

Tesis (Maestro en Ciencias con especialidad en Entomología Médica) U.A.N.L.

Molecular comparisons of the Culex pipiens (L.) complex esterase gene amplicons

The amplification of carboxylesterase genes is a mechanism of organophosphate resistance in Culex mosquitoes. Amplified carboxylesterase genes from an insecticide resistant Culex pipiens strain collected in Cyprus were analysed and compared to other Culex amplified carboxylesterase alleles. A 12 kb section of genomic DNA containing two gene loci coding for carboxylesterase alleles A5 and B5 was cloned and sequenced. A comparison between this amplicon and one from a strain with co-amplified carboxylesterase alleles A2 and B2 revealed a number of differences. The intergenic spacer was 3.7 kb in length in the A5-B5 amplicon (2.7 kb in A2-B2) and contained putative Juan and transposable elements upstream of B5. A fragment of a gene with high homology to aldehyde oxidase was also present immediately downstream of A5. The comparison revealed no differences that would explain the successful spread of the A2-B2 amplicon worldwide whilst the A5-B5 amplicon is restricted to the Mediterranean. (C) 2004 Elsevier Ltd. All rights reserved.

Morphological and fecundity traits of Culex mosquitoes caught in gravid traps in urban and rural Berkshire, UK

Culex pipiens s.l. is one of the primary vectors of West Nile Virus in the USA and Continental Europe. The seasonal abundance and eco-behavioural characteristics of the typical form, Cx. pipiens pipiens, make it a key putative vector in Britain. Surveillance of Culex larvae and adults is essential to detect any changes to spatial and seasonal activity or morphological traits that may increase the risk of disease transmission. Here we report the use of the modified Reiter gravid box trap, which is commonly used in the USA but scarcely used in the UK, to assess its suitability as a tool for British female Culex mosquito surveillance. Trapping was carried out at 110 sites in urban and rural gardens in Berkshire in May, July and September 2013. We tested if reproductively active adult female Culex are more abundant in urban than rural gardens and if wing characteristic traits and egg raft size are influenced by location and seasonal variations. Gravid traps were highly selective for Culex mosquitoes, on average catching significantly more per trap in urban gardens (32.4 ± 6.2) than rural gardens (19.3 ± 4.0) and more in July than in May or September. The majority of females were caught alive in a good condition. Wing lengths were measured as an indicator of size. Females flying in September were significantly smaller than females in May or July. Further non-significant differences in morphology and fecundity between urban and rural populations were found that should be explored further across the seasons.

Culex pipiens development is greatly influenced by native bacteria and exogenous yeast

Culex pipiens is the most cosmopolitan mosquito of the Pipiens Assemblage. By studying the nature of interactions between this species and microorganisms common to its breeding environment we can unravel important pitfalls encountered during development. We tested the survival rate of larval stages, pupae and adults of a Cx. pipiens colony exposed to a variety of microorganisms in laboratory conditions and assessed the transmission to offspring (F1) by those organisms that secured development up to adulthood. Three complementary experiments were designed to: 1) explore the nutritional value of yeasts and other microorganisms during Cx. pipiens development; 2) elucidate the transstadial transmission of yeast to the host offspring; and 3) to examine the relevance of all these microorganisms in female choice for oviposition-substratum. The yeast Saccharomyces cerevisiae proved to be the most nutritional diet, but despite showing the highest survival rates, vertical transmission to F1 was never confirmed. In addition, during the oviposition trials, none of the gravid females was attracted to the yeast substratum. Notably, the two native bacterial strains, Klebsiella sp. and Aeromonas sp., were the preferred oviposition media, the same two bacteria that managed to feed neonates until molting into 2nd instar larvae. Our results not only suggest that Klebsiella sp. or Aeromonas sp. serve as attractants for oviposition habitat selection, but also nurture the most fragile instar, L1, to assure molting into a more resilient stage, L2, while yeast proves to be the most supportive diet for completing development. These experiments unearthed survival traits that might be considered in the future development of strategies of Cx. pipiens control. These studies can be extended to other members of the Pipiens Assemblage

Taxonomic and Phylogenetic Relationships Between Species of the Genus Culex (Diptera: Culicidae) From Brazil Inferred From the Cytochrome c Oxidase I Mitochondrial Gene

Species of the genus Culex Linnaeus have been incriminated as the main vectors of lymphatic filariases and are important vectors of arboviruses, including West Nile virus. Sequences corresponding to a fragment of 478 bp of the cytochrome c oxidase subunit I gene, which includes part of the barcode region, of 37 individuals of 17 species of genus Culex were generated to establish relationships among five subgenera, Culex, Phenacomyia, Melanoconion, Microculex, and Carrollia, and one species of the genus Lutzia that occurs in Brazil. Bayesian methods were employed for the phylogenetic analyses. Results of sequence comparisons showed that individuals identified as Culex dolosus, Culex mollis, and Culex imitator possess high intraspecific divergence (3.1, 2.3, and 3.5%, respectively) when using the Kimura two parameters model. These differences were associated either with distinct morphological characteristics of the male genitalia or larval and pupal stages, suggesting that these may represent species complexes. The Bayesian topology suggested that the genus and subgenus Culex are paraphyletic relative to Lutzia and Phenacomyia, respectively. The cytochrome c oxidase subunit I sequences may be a useful tool to both estimate phylogenetic relationships and identify morphologically similar species of the genus Culex.

Two new species of Culex subgenus Melanoconion (Diptera: Culicidae) from the Amazon forest

Two new mosquito species (Diptera: Culicidae), Culex (Melanoconion) phyllados n. sp. and Culex (Melanoconion) brachiatus n. sp. from the state of Amazonas, Brazil, are here validated and described based on morphological features of the male genitalia. Both species are morphologically more similar to both Culex coppenamensis Bonne-Wepster & Bonne and Culex alinkios Sallum & Hutchings than to any other species of the Bastagarius Subgroup of the subgenus Melanoconion. Diagnostic characters for the identification of the adult male of both species are provided.

Redescription of Culex (Culex) dolosus (Lynch Arribalzaga) (Diptera : Culicidae), based on specimens from Pico do Itapeva, Serra da Mantiqueira, Sao Paulo, Brazil

Culex (Culex) dolosus (Lynch Arribalzaga, 1891) is re-described and compared with Cx. eduardoi Casal & Garcia ( 1968) based on morphological characteristics. Both species are morphologically similar, and they have been largely misidentified throughout Brazil. Adult male and female, fourth instar larvae, and pupae of Cx. dolosus were examined, based on specimens from Pico do Itapeva, Pindamonhangaba Municipality, Serra da Mantiqueira, Sao Paulo State, southern Brazil. Male genitalia, larvae and pupae are illustrated. Geographical distribution is summarized from published records, and information on bionomics is based on the literature and field data.

First Identification of Culex flavivirus (Flaviviridae) in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

First Identification of Culex flavivirus (Flaviviridae) in Brazil

Introduction: Culex flavivirus (CxFV) was first isolated in 2007 from Culex pipiens in Japan and then identified in several other countries. Characterization of the CxFV showed that all strains are related to the cell fusing agent virus. In this manuscript we report the first identification of CxFV in South America. Material and Methods: We have collected Culex sp. mosquitoes using BG-Sentinel traps and manual aspirators. They were pooled according to genus, species, sex and location. Viral RNA was extracted and multiplex nested PCR was performed to test the presence of Flavivirus. The positive samples were isolated in C6/36 cells and sequenced for phylogenetic analyses. Results: 265 female Culex mosquitoes pooled in 83 pools were tested with specific CxFV, Saint Louis encephalitis virus (SLEV) and West Nile virus (WNV) primers. Our sequence data indicated maximum sequence similarity of 97% with CxFV. Discussion: In this study we report the circulation of CxFV in an urban setting where SLEV had previously caused an outbreak. In terms of public health, this is an important finding due to the assumption that the previous exposition of mosquitoes to CxFV might lessen the susceptibility of these mosquitoes to other flaviviruses. Copyright (C) 2012 S. Karger AG, Basel

Vejez y parodia en el Culex

Frente a la afirmación tradicional que clasifica el Culex como parodia del género épico y al aporte de Ross (1975), para quien el poema parodia, saturándolos, los clichés narrativos neotéricos, el trabajo postula, mediante el análisis de los versos 15 del proemio y de su lineamiento argumental, que el poema se presenta y se desarrolla como una combinación lúdica de los géneros asociados al hexámetro (bucólico, épico, didácticogeórgico). En este sentido, la construcción de la vejez del protagonista que es sucesivamente pastor, guerrero, campesinose apoya en un diálogo con sus emblemáticas contrapartidas virgilianas: Títiro, Príamo, el viejo de Tarento.

Vejez y parodia en el Culex

Frente a la afirmación tradicional que clasifica el Culex como parodia del género épico y al aporte de Ross (1975), para quien el poema parodia, saturándolos, los clichés narrativos neotéricos, el trabajo postula, mediante el análisis de los versos 15 del proemio y de su lineamiento argumental, que el poema se presenta y se desarrolla como una combinación lúdica de los géneros asociados al hexámetro (bucólico, épico, didácticogeórgico). En este sentido, la construcción de la vejez del protagonista que es sucesivamente pastor, guerrero, campesinose apoya en un diálogo con sus emblemáticas contrapartidas virgilianas: Títiro, Príamo, el viejo de Tarento.

Vejez y parodia en el Culex

Frente a la afirmación tradicional que clasifica el Culex como parodia del género épico y al aporte de Ross (1975), para quien el poema parodia, saturándolos, los clichés narrativos neotéricos, el trabajo postula, mediante el análisis de los versos 15 del proemio y de su lineamiento argumental, que el poema se presenta y se desarrolla como una combinación lúdica de los géneros asociados al hexámetro (bucólico, épico, didácticogeórgico). En este sentido, la construcción de la vejez del protagonista que es sucesivamente pastor, guerrero, campesinose apoya en un diálogo con sus emblemáticas contrapartidas virgilianas: Títiro, Príamo, el viejo de Tarento.

Revisão da seção Spissipes de Culex (Melanoconion) (Diptera: Culicidae)

Apresenta-se estudo revisionário da Seção Spissipes de Culex (Melanoconion), onde são feitas descrições de formas adultas, incluídos as genitálias de ambos os sexos e o cibário das fêmeas. Sob o ponto de vista taxonômico, considera-se a existência atual de 22 espécies válidas das quais duas são consideradas como novas. Culex nicaroensis Duret foi retirada pois, a análise de suas características morfológicas permitiu alegar a conclusão de não pertencer ao subgênero Melanoconion, ficando sem reconhecimento subgenérico. Além disso, procedeu-se ao estabelecimento da sinonímia de Culex alvarezi Sutil Oramas, Pulido Florenzano & Amarista Menezes com Culex spissipes (Theobald). Levando em consideração vários caracteres das formas supramencionadas, pôde-se subdividir a Seção em grupos e subgrupos, mediante afinidades morfológicas que, à luz dos atuais conhecimentos, permite serem ponderadas. Sob o ponto de vista biogeográfico são apresentados os dados disponíveis, daí resultando mapas de distribuição. A importância epidemiológica desse grupo de culicídeos é apresentada mediante o levantamento dos conhecimentos obtidos até agora na literatura. Foram elaboradas chaves para identificação específica.